This application claims the benefit of Korean Patent Application No. 10-2004-0110352, filed on Dec. 22, 2004 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method of constituting and protecting control channels, and particularly, to a method of constituting and protecting control channels in for constituting a highly reliable control network IP-based networks.
2. Description of the Related Art
Best-effort based IP networks use routing protocols such as OSPF and BGP in order to forward data packets. In this situation, control packets generated by routing protocols are processed in the layer 3 as the same way that data packets exchanged by ordinary users are done in the layer. It means that channels carrying data and control packets share the fate. MPLS based IP networks developed from the best-effort based IP networks use routing and signaling protocols to establish LSPs that are determined for more effectively forwarding data packets. However, their control packets are still processed in the layer 3, and the fate of control channels is the same to that of data channels as well.
Then, GMPLS based IP networks come to be capable of handling control channels separated from data channels. It means that channels carrying data and control packets have an impact upon each other. Several control channels such as SONET/SDH DCC channels and Ethernet OAM channels defined by the OIF, MPLS based LSPs as dedicated control channels, public IP networks, out-of-fiber based dedicated control channels, and so on can be configured independent from data channels for the purpose.
Putting the trend together, a node can keep control channels of sharing and separated fate simultaneously, and a network can provide the protection function of various levels based on configuration schemes of paths to be used to exchange control packets between adjacent nodes. For examples, the IETF configure and manage control channels using the LMP protocol as a typical protocol in GMPLS. But, this protocol uses paths over direct-connected interfaces between nodes or over out-of-fiber based control channels. It means that the protocol does not use a detour route over indirect-connected interfaces between nodes. The MPLS based method uses two MPLS LSPs as dedicated control channels to send control packets over them at the same time. Then, a receiving side takes first-arrived packets and discards late-arrived packets. But, it is difficult to apply this scheme to all network elements within a network, and the scheme has a disadvantage that traffic of control packets increase in double.